Fixing bugs and removing debug statements

[tpg/acess2.git] / Kernel / arch / x86 / lib.c

diff --git a/Kernel/arch/x86/lib.c b/Kernel/arch/x86/lib.c
index 6522574..c499c7a 100644 (file)
--- a/Kernel/arch/x86/lib.c
+++ b/Kernel/arch/x86/lib.c
@@ -121,10 +121,15 @@ void *memcpyd(void *Dest, const void *Src, size_t Num)
  */
 Uint64 __udivdi3(Uint64 Num, Uint64 Den)
 {
-       Uint64  ret = 0;
+       Uint64  P[2];
+       Uint64  q = 0;
+        int    i;
        
-       if(Den == 0)    __asm__ __volatile__ ("int $0x0");      // Call Div by Zero Error
-       if(Den == 1)    return Num;     // Speed Hacks
+       if(Den == 0)    __asm__ __volatile__ ("int $0x0");
+       // Common speedups
+       if(Num <= 0xFFFFFFFF && Den <= 0xFFFFFFFF)
+               return (Uint32)Num / (Uint32)Den;
+       if(Den == 1)    return Num;
        if(Den == 2)    return Num >> 1;        // Speed Hacks
        if(Den == 4)    return Num >> 2;        // Speed Hacks
        if(Den == 8)    return Num >> 3;        // Speed Hacks
@@ -133,19 +138,33 @@ Uint64 __udivdi3(Uint64 Num, Uint64 Den)
        if(Den == 1024) return Num >> 10;       // Speed Hacks
        if(Den == 2048) return Num >> 11;       // Speed Hacks
        if(Den == 4096) return Num >> 12;
+       if(Num < Den)   return 0;
+       if(Num < Den*2) return 1;
+       if(Num == Den*2)        return 2;
        
-       if(Num >> 32 == 0 && Den >> 32 == 0)
-               return (Uint32)Num / (Uint32)Den;
-       
-       //Log("__udivdi3: (Num={0x%x:%x}, Den={0x%x:%x})",
-       //      Num>>32, Num&0xFFFFFFFF,
-       //      Den>>32, Den&0xFFFFFFFF);
-       
-       while(Num > Den) {
-               ret ++;
-               Num -= Den;
+       // Restoring division, from wikipedia
+       // http://en.wikipedia.org/wiki/Division_(digital)
+       P[0] = Num;     P[1] = 0;
+       for( i = 64; i--; )
+       {
+               // P <<= 1;
+               P[1] = (P[1] << 1) | (P[0] >> 63);
+               P[0] = P[0] << 1;
+               
+               // P -= Den << 64
+               P[1] -= Den;
+               
+               // P >= 0
+               if( !(P[1] & (1ULL<<63)) ) {
+                       q |= (Uint64)1 << (63-i);
+               }
+               else {
+                       //q |= 0 << (63-i);
+                       P[1] += Den;
+               }
        }
-       return ret;
+       
+       return q;
 }
 
 /**
@@ -168,9 +187,7 @@ Uint64 __umoddi3(Uint64 Num, Uint64 Den)
        if(Num >> 32 == 0 && Den >> 32 == 0)
                return (Uint32)Num % (Uint32)Den;
        
-       while(Num > Den)
-               Num -= Den;
-       return Num;
+       return Num - __udivdi3(Num, Den) * Den;
 }
 
 Uint16 LittleEndian16(Uint16 Val)